Field of the Invention
The present invention relates to an image forming apparatus with an attachable/detachable duplex unit, a control method therefor, and a storage medium.
Description of the Related Art
Conventionally, there has been known an image forming apparatus with an attachable/detachable duplex unit having an inversion conveying path and others for performing double-sided printing. This image forming apparatus is configured to be capable of detecting that the duplex unit is attached using a sensor, and upon receiving image data for double-sided printing in a state where attachment of the duplex unit has not been detected, display error information and stop a printing process.
There is also known an image forming apparatus which is configured to, when a duplex unit is attached in a state where attachment of the duplex unit has not been detected, carry out a printing process on print data which has been suspended until then (Japanese Laid-Open Patent Publication (Kokai) No. 2006-35564). According to Japanese Laid-Open Patent Publication (Kokai) No. 2006-35564, in a case where one-sided printing is performed, printing is possible even when the duplex unit is not attached, and hence a printing process for a one-sided print job is carried out without being suspended.
However, in an image forming apparatus with an attachable/detachable duplex unit when the duplex unit is not completely attached, there may be cases where the duplex unit is mechanically placed at an attachment position although attachment of the duplex unit has not been electrically detected. In such cases, according to a result of detection using a sensor, the duplex unit is not attached, and hence double-sided printing is not performed. However, when a one-sided print job is to be executed, arrangements for transmission of drive systems and configurations of conveying paths are intended for double-sided printing although in terms of control, control suitable for one-sided printing is provided, and as a result, one-sided printing may not be properly performed, causing a sheet jam. This may cause damage to the image forming apparatus.
Specifically, “a state where the duplex unit is completely detached” and “a state where the duplex unit is not completely attached although a user feels that he or she has attached the duplex unit” cannot be distinguished from each other by means of electric detection. Therefore, it is preferable to provide printing control with consideration given to both of these two states.